The present invention relates to management of a distributed power supply system, and more particularly to the control and monitoring of an array of point-of-load regulators or other non-isolated DC-DC converters within a distributed power supply system.
With the development of the electronic and communication technology, the power supply system is becoming more complex. As a result, the requirements of power density and reliability of the power supply system are getting higher as well. It is common for an electronic system to require several different relatively low voltage levels, such as 3.3V, 2.5V, 1.8V, 1.2V, etc., and the voltage should be regulated precisely. At the same time, relatively high current levels (e.g., 100 A) and high current changing rates (e.g., 1000 A/μs) are also required. It's not a good way to deliver such a high current to electronic devices over a long distance, because the impedance of the lines carrying the high current tends to dissipate a large part of power and deteriorate the load regulation. So, the physical distance between the power supply and its load should be as short as possible to avoid significant power loss and to make sure of the system stability. That means the traditional multi-output power supplies which are not close enough to different loads can't satisfy the requirements.
In order to solve the problems above, at present the distributed power supply system with an intermediate bus configuration is widely used. This system comprises two stages. In the first stage, the AC input voltage for the whole system is rectified, then converted to the intermediate bus voltage level (the typical value is 8-12V), and electrical isolation is also realized in this stage. There are multiple non-isolated point-of-load (POL) regulators in the second stage, and each of them converts the intermediate bus voltage to each of the multiple levels required by the electronic system. This configuration that each relatively low power POL regulator is located close to a particular electronic device will help improve the system efficiency and reliability.
A typical distributed power supply system includes multiple POL regulators. With this approach, the management of these POL regulators becomes very important. There is a need to control and monitor different operating parameters accurately, and diagnose fault conditions quickly of every POL regulator to get excellent performance of the whole distributed power supply system. At present, there are mainly three kinds of manager to control the POL regulators in the distributed system: analog controller, digital power system sequencer and multi-digital controllers.
In a conventional power supply system, all POL regulators are controlled by analog control methods. Analog control is a very mature technology and has relatively low cost, and therefore it has wide applications in distributed power supply system architectures. One drawback of an analog control system is that it is difficult for a host computer to get the working status of each POL regulator and to realize on-line control.
In order to make up for the shortcomings of conventional analog control, a control configuration which includes a digital signal processor (DSP) or micro control unit (MCU) based digital power system sequencer is utilized. In this approach, the POL regulators closed-loop voltage control is also implemented by analog devices, and a host computer manages all POL regulators through the digital power system sequencer. The instructions transmitted from the host computer to program POL regulators operating parameters and the monitoring data sent from the digital power system sequencer are all transferred via the power management bus (PMBus) which is based on the PMBus protocol—an open standard communication protocol. The digital power system sequencer is capable of sensing the output voltage, controlling the ON/OFF state, and sequencing and margining the output voltage of each POL regulator via various kinds of peripherals integrated on the DSP/MCU. The digital power system sequencer further comprises a PMBus interface adapted to communicate with the host computer. The number of POL regulators can be managed depends on the amount of the peripherals integrated on the DSP/MCU. Although the on-line management is implemented, the closed-loop voltage control is not flexible because of the analog closed-loop voltage control.
With the increasing calculation speed of the DSP/MCU, a kind of distributed power supply system with multiple digital controllers is also used. In this system, each of the multiple digital controllers is responsible to each of the multiple POL regulators for individual closed-loop control and various protections, and furthermore, as a slave device, each digital controller can have bidirectional communication with the host computer. This control implementation has on-line management functions similar to the above-described approach, and it also improves the system design flexibility. However, for every POL regulator a corresponding digital controller is required with adequate integrated peripherals and communication interfaces. Overall system cost may be high, and the communication efficiency may be low due to too many devices in the system.
Thus, it would be advantageous to have a management system and method for controlling and monitoring power converters within a distributed power supply system.